Whales have what seem like remnants of a pelvis and femur, as shown here.

An x-ray image of a whale tail. The pelvis and femur bones are shown.

What are these structures an example of?
transitional structures
analogous structures
vestigial structures
adapted structures

c. establishing proper sleep hygiene

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.

the answer is

for a different answer set the answer would be because the oxygen in the water had depleted (apex)